1. Field of the Invention
The present invention relates to image processing. Particularly, the present invention relates to an image processing method, apparatus, and program for making users check the condition of blurs in digital photograph images.
2. Description of the Related Art
Digital photograph images (hereinafter, referred to as photograph images or images, for short) are obtained by photoelectrically reading out photograph images recorded on photograph films such as negative films and color reversible films with a readout device such as a scanner. Digital photograph images are also obtained by photographing subjects with digital still cameras (DSC). When the digital photograph images are obtained, blurs are present in some of the digital photograph images. When photograph images are obtained by photographing a subject, the images may become fuzzy because of an out-of-focus blur or a blur due to hand motion of a photographer. The out-of-focus blur is created when focal length is not adjusted appropriately, whereas the blur due to hand motion is created when a camera is moved because of the motion of the hands of the photographer (hereinafter referred to as a motion blur, for short). If a blur is an out-of-focus blur, a point image spreads two-dimensionally. In other words, the out-of-focus blur spreads non-directionally in the photograph image. However, if the blur is a motion blur, the point image traces a certain locus, and the point image spreads linearly in the image. In other words, the motion blur spreads directionally in the photograph image.
As cellular phones rapidly became popular in recent years, the performance of the cellular phones has improved. Especially, an improvement in the performance of digital cameras (hereinafter referred to as cellular cameras, for short) attached to the cellular phones is remarkable. Recently, the number of pixels of the cellular cameras exceeded one million. Therefore, the cellular cameras are used in a similar manner to ordinary digital cameras. When people travel with their friends, they often use their cellular cameras to take their photographs. Further, many users of the cellular phones take photographs of their favorite TV stars or athletes with their cellular cameras. Under these circumstances, many users of the cellular phones who enjoy the photographs obtained with their cellular cameras by displaying them on the monitors of their cellular phones also print the photographs in a similar manner to printing of those obtained with ordinary digital cameras.
However, since the main bodies (cellular phones) of the cellular cameras are not ergonomically designed as specialized photography apparatuses, there is a problem that it is not easy to hold the cellular phones during photography. Further, since no strobes are provided in the cellular cameras, the shutter speeds of the cellular cameras are slower than those of the ordinary digital cameras. Therefore, when a photograph of a subject is taken with a cellular camera, a possibility that a motion blur is created in the obtained image is high in comparison with photography with ordinary cameras. Since the monitor of the cellular phone is small, when an image obtained by photography with a cellular camera is displayed on the monitor to check the image, the size of the image is reduced. Therefore, if a large motion blur is present in the image, the photographer can detect the motion blur in the monitor. However, if a small out-of-focus blur or motion blur is present in the image, he/she often notices the blur only after the image is printed. Therefore, various methods have been proposed to correctly check the condition of a blur in a image by displaying it on a small monitor such as monitors of the cellular phones.
For example, among digital cameras which are on sale, there are digital cameras in which the condition of blurs can be more easily checked by making the users of the digital cameras specify display regions in images obtained by photography. In these digital cameras, the users display the images of the specified display regions on the monitors of the digital cameras at a 1:1 magnification ratio or by enlarging them.
Alternatively, as disclosed in U.S. Patent Application Publication No. 20030184667, a method for extracting an image of a predetermined region such as the central region of the image, and displaying it at a 1:1 magnification ratio has been proposed. Further, a method for dividing the image into a plurality of regions and sequentially displaying them at a 1:1 magnification ratio has been proposed.
However, in the method of making users specify display regions, the users are required to specify the regions which will be checked, and that is troublesome for the users. Further, in the method of making the users specify display regions, the users cannot always accurately specify the regions which are appropriate for checking blurs. Therefore, even if an image is a blurred image, the users may erroneously judge that the image is an image without a blur.
Further, in a method of displaying a region at a predetermined position of an image by extracting it from the image, as disclosed in U.S. Patent Application Publication No. 20030184667, there is a problem that if the region at the predetermined position of the image is not appropriate for checking blurs, the users cannot accurately judge the condition of the blurs. Further, in the method of dividing an image into a plurality of regions and sequentially displaying the divided regions, there is a problem that a long time is required for processing, and that is troublesome for the users.